sp. nov. and sp. nov., novel bacterial species with versatile natural product biosynthesis potential isolated from marine sponges.

This study describes two Gram-negative, flexirubin-producing, biofilm-forming, motile-by-gliding and rod-shaped bacteria, isolated from the marine sponges and collected off the coast of Algarve, Portugal. Both strains, designated Aq135 and Aq349, were classified into the genus by means of 16S rRNA gene sequencing. We then performed phylogenetic, phylogenomic and biochemical analyses to determine whether these strains represent novel species. Whereas the closest 16S rRNA gene relatives to strain Aq135 were JAMB N27 (97.8 %) and w01 (97.1 %), strain Aq349 was more closely related to XH134 (99.2 %) and 22II-S11-z7 (98.1 %). Both strains showed genome-wide average nucleotide identity scores below the species level cut-off (95 %) with all type strains with publicly available genomes, including their closest relatives. Digital DNA-DNA hybridization further suggested a novel species status for both strains since values lower than 70 % hybridization level with other type strains were obtained. Strains Aq135 and Aq349 grew from 4 to 30°C and with between 1-5 % (w/v) NaCl in marine broth. The most abundant fatty acids were iso-C3-OH and iso-C and the only respiratory quinone was MK-6. Strain Aq135 was catalase-positive and β-galactosidase-negative, while Aq349 was catalase-negative and β-galactosidase-positive. These strains hold unique sets of secondary metabolite biosynthetic gene clusters and are known to produce the peptide antibiotics aquimarins (Aq135) and the trans-AT polyketide cuniculene (Aq349), respectively. Based on the polyphasic approach employed in this study, we propose the novel species names sp. nov. (type strain Aq135=DSM 115833=UCCCB 169=ATCC TSD-360) and sp. nov. (type strain Aq349=DSM 115834=UCCCB 170=ATCC TSD-361).